I3S THE DISPERSAL OF SHELLS. 



of the peninsula of Florida and the adjacent islands : 

 Mr. W. G. Binney, however, writing of ^. undatiis, has 

 suggested that the creature may have been a widely 

 distributed species of an ancient fauna, which has 

 survived at various points around the gulf of Mexico.^ 

 Unfortunately I do not know that any observa- 

 tion clearly indicating the transportal of molluscs, or 

 their eggs, with drift-timber, etc., has ever been made. 

 The creatures have never been found, as far as I have 

 ascertained, in the crevices or under the bark either of 

 trees encountered upon the sea, or of those stranded on 

 foreign coasts. Important discoveries may possibly be 

 made, however, by some traveller who applies himself 

 to the careful examination of a large number of such 

 trees. Mr. Layard tells me that landing on one 

 occasion on '^a lone, sandy island in the Indian Ocean, 

 north of Madagascar/' he found on the shore a huge 

 tree-trunk, '^just arrived from the African Coast," 

 swarming with ants, and containing in a crevice the 

 living eggs of a lizard, probably a gecko ! 



Rivers and Floods. 



No doubt, as Mr. Wallace observes, terrestrial molluscs 

 have been " widely scattered over land areas " by '^ large 

 rivers and occasional floods."' From considerations 

 above referred to it is obvious, of course, that both adults 



^ A. Binney, "Terrestrial air-breathing Mollusks," i. (1851), 

 p. 153 ; ii. (185 1), pp. 270, 274 ; W. G. Binney, v. (1878), p. 409 ; 

 C. T. Simpson, " Conchologists' Exchange," ii. (1887), P- 3S- 



^ " Geographical Distribution," ii. p. 525. 



